Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$148.88	8.603%	$161.6881	$161.69	$161.70	$161.70
Purchase #2	$213.32	9.814%	$234.2552	$234.26	$234.25	$234.30
Purchase #3	$22.55	9.160%	$24.6156	$24.62	$24.60	$24.60
Purchase #4	$208.82	3.719%	$216.586	$216.59	$216.60	$216.60
Purchase #5	$187.53	6.729%	$200.1489	$200.15	$200.15	$200.10
Purchase #6	$41.72	9.112%	$45.5215	$45.52	$45.50	$45.50
Purchase #7	$158.42	12.497%	$178.2177	$178.22	$178.20	$178.20
7 purchase totals =	$981.24		$1,061.0330	$1,061.05	$1,061.00	$1,061.00